The invention relates to a containmant with a long-time corrosion resistant protective cover for tightly sealed containers with highly radioactive content such as steel containers enclosing radioactive waste molten into glass or burnt-out fuel elements of nuclear reactors.
The invention also is concerned with the manufacture of a mechanically, chemically and thermally stable packaging including a safe barrier for the isolation of environmentally dangerous materials in geologic formations. It is concerned in this connection with the final storage of highly radioactive waste encased in molten glass in deep bore holes of salt formations.
Highly radioactive glass-encased waste has not yet been placed into final storage. The packaging used so far for highly radioactive waste materials does not fulfill the barrier requirements for long-time isolation in final storage locations.
The barrier systems presently employed, which include outer corrosion protection, have the following disadvantages:
The corrosion protective enclosure is not in full contact with the steel container which forms the structure resistant to mechanical damage. The enclosure is therefore subject to damage as a result of thermal expansion or by exposure to outer forces as they may be caused by collapse of the storage bore. The enclosure is especially sensitive in areas where it is not in contact with the container, as adjacent the lid and cylinder section of the container and adjacent the bottom and cylinder section of the container.
With this kind of corrosion protection, which is applied in the form of a protective layer, welding of narrow-groove joints must be performed under cover gas in order to provide for weld seam quality with regard to corrosion resistance which is comparable with non-welded corrosion protective structures. However, sufficient cover gas protection cannot be guaranteed under the given conditions. The requirements for a corrosion protection structure which is tightly joined to the inner steel container and which permits good cover gas flushing of the weld joint are actually opposing one another. Stacking of such containmants in a drill hole causes crevice corrosion problems since the corrosion protective structure of one container comes in direct contact with the corrosion protective structure of the container stacked on top. If a grapping structure is arranged above the containers they cannot accept the load upon stacking. Also the provision of a grapping structure represents a weak point for the containment as far as corrosion protection is concerned. Fixing of such a containment in a transport container in which the lid and the bottom of the containment are at the same time top and bottom of a radiation shielding structure is not possible without adversely affecting the corrosion protection means.
It is the object of the present invention to provide a long-time corrosion protection enclosure for containments with highly radioactive content which does not have the disadvantages referred to above and which insures safe enclosure of the highly radioactive materials over a long period of time.